1. Field of the Invention
The invention relates to a hollow shaft having drive elements partly formed of brittle material, being secured on the hollow shaft by expansion of sections of the hollow shaft.
2. Description of the Related Art
In Published European Patent Application No. 0 213 529, corresponding to allowed U.S. application Ser. No. 900,387, filed Aug. 26, 1986, now U.S. Pat. No. 4,750,250 having an inventor in common with the instant application, a method has been proposed for fastening drive elements, such as cams, gear wheels or bearing bushings, on a hollow shaft. The hollow shaft is a commercially available pipe or tubing, onto which the elements are slipped and then secured by expansion of the sections of the tubing located beneath them. In order to avoid expensive subsequent finishing of the shaft after assembly, the drive elements should already be largely completely machined prior to assembly. This may also include hardening of the surface thereof. In order to seat the drive elements firmly on the shaft, the shaft must be deformed plastically by the expansion process, while the deformation of the drive elements remains in the elastic range, so that they can spring back at the end of the expansion process. It has now been demonstrated that the hardened surface of the drive elements tends to form fissures during the elastic deformation thereof.